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Diagram of the human hand, from Giordano Bruno's discussion of the properties of the number 5 in De monade numero et figura.

Abstract

De monade numero et figura (On the Monad, Number and Figure) is part of the trilogy of Latin verse works published in Frankfurt in 1591 and considered to be Bruno's philosophical testament. In the De monade Bruno discusses Pythagorean number symbolism and the meanings of the numbers 1 to 10.

This translation from the original Latin is by Edmund Cullen. It includes notes and illustrations by Cullen and was published in 1784 by J. Murray, London.

ID number

RB-TB1784

Title

Portrait of Giovanni Domenico Cassini

Abstract

Portrait of Cassini from his account of his heliometer in Bologna, published 40 years after its installation in La Meridiana del tempio di S. Petronio..., 1695.

ID number

RB-GC1695-1

Title

Cassini's heliometer

Abstract

The church of San Petronio in Bologna was the site of a solar observatory as early as 1576 when Egnazio Danti, cosmographer to Cosimo I de' Medici, installed the first meridian line there. Unfortunately it did not fulfill its purpose, which was to provide an accurate date for the spring equinox, thence Easter. In spite of uncertainties about the precise length of the solar year, the Gregorian calendar was promulgated anyway, in 1582. We still use it today. Almost 75 years later, the opportunity arose to reconstruct the meridian. Enter a 29-year-old astronomy professor named Giovanni Domenico Cassini. Cassini increased the height of Danti's solar peephole—or gnomon hole—to 1000 inches (based on the French foot) or 27.07 meters above the church floor. The length of the meridian line was increased by x2.5 to 66.71 meters, or 1/600,000 of the Earth's circumference, per Cassini's calculation. The line had to run on the floor between the aisles and columns of the church on a north-south axis without obstruction. The instrument was tested with great fanfare at the summer solstice of 1655 and proved fully successful. Cassini's illustrated account of his heliometer was published 40 years later in 1695 with the title La Meridiana del tempio di S. Petronio. The image shown here is taken from a large foldout plate depicting the design and details of installation.

ID number

RB-GC1695-2

Title

Engraving designed by Kepler

Abstract

Engraved frontispiece to Kepler's Rudolphine Tables (Tabulae Rudolphinae) showing the great astronomers (including Kepler) gathered in the temple of Urania. Designed by Kepler himself; engraved by Georg Celer.

An engraved illustration of features of the moon's surface, as seen by Galileo with his telescope. He was able to describe the roughness of the moon's surface and the position of spots and prominences on the light and dark sides.

ID number

RB-GG1610a-3

Title

Galileo, two illustrations of the moon from Sidereus Nuncius (The Sidereal Messenger), Venice, 1610

Abstract

Two illustrations of features of the moon's surface, showing strong light and dark shadings on the light side. According to the prevailing Aristotelian cosmology, heavenly bodies were perfectly smooth and spherical. Galileo's observations of the moon's roughness tended to support the new Copernican system, which no longer upheld the distinction between terrestrial and heavenly bodies.

Hamilton, Sir William, “Campi Phlegraei: Observations on the Volcanos of the Two Sicilies, plate 9.

Abstract

One of 54 plates by Peter Fabris illustrating volcanis activity in the region of Naples. Sir William Hamilton was at this time royal envoy to the Count of Naples and published his investigations of volcanos for the Royal Society.

ID number

RB-WH1779-1

Title

Hamilton, Sir William, “Campi Phlegraei: Observations on the Volcanos of the Two Sicilies, plate 37.

Abstract

One of 54 plates by Peter Fabris illustrating volcanis activity in the region of Naples. Sir William Hamilton was at this time royal envoy to the Count of Naples and pubished his investigations of volcanos for the Royal Society.

ID number

RB-WH1779-2

Title

Illustration from Kepler's "Harmonices Mundi" (Harmonies of the World).